It is known to use a silica gel support for reversed phase chromatography (hereafter referred to as reversed phase support) coated with an amino acid derivative as a medium for optical resolution, as described, e.g., in V. A. Davankov, Chromatographia, Vol. 13, 667 (1980) or JP-A-58-96062 (The term "JP-A" as used herein means an "unexamined published Japanese patent application"). The references teach use of an N-alkyl derivative of proline or hydroxproline for coating the support.
However, difficulty arises in coating these amino acid derivatives on the reversed phase support because they have high crystallinity and, therefore, low solubility in an aqueous alcohol solution chiefly employed for the coating. Besides, the coated packing material exhibits so poor stability that the amino acid derivative carried on the support falls off during long-term use, resulting reduction of optical resolution ability. Further, this packing, although excellent in resolution of specific amino acids, scarecely manifests the resolving ability to hydrophilic amino acids, such as serine, histidine, lysine, glutamic acid, etc.